<!-- <script>
    let date = window.prompt('input');
    switch(date) {
        case "Monday":
        case "Tuesday":
        case "Wednesday":
        case "thursday":
        case "Friday":
            console.log("working");
            break;
        case "":
        case "":
            console.log("relaxing");
            break;
    }

    for(let i = 0; i < 100; i++){
        if (i > 80) {
            document.write(i);
            break;
        }
    }
    console.log(Number(null));  //0
    console.log(Number(undefined)); // NaN
    //  typeof 返回 number string boolean object undefined function
    //null 数组用 typeof返回object
    // undefined 返回undefinned
    // 类型转换

    isNaN(NaN); //内部调用的是Number()

    // ++/--   +/-(一元正负) Number()
    // -*/%     Number()
    // < > >= <=     Number()
</script> -->

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<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
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    <title>Document</title>
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    alert(getName());
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